Signals and Sensors: Are particular Magnaporthe grisea cutinases pivotal in host perception priming signal relay and pathogenicity?

Fungi are the most important and destructive 'agents' of plant disease. Indeed, a serious and recurrent problem is caused by the rice blast fungus Magnaporthe grisea, which annually destroys sufficient rice to feed the population of GB, presupposing that our staple diet depended on this grain alone. Much is known about the biology of the fungal infection process and scientists recently reported its genome sequence. This fungus serves as an excellent model system for understanding the 'goings-on' between plant and pathogen. In this proposal we seek to understand whether the fungus 'talks' to the plant via a mechanism / series of cutinase enzymes which specifically degrade the plant cuticle and whether the cuticle breakdown products signal back to the fungus to make it form its leaf infection structures. Moreover, we know thatseveral of these cutinases exist in the rice blast fungus and we seek to understand whether one is involved in penetration of the host plant.

The recent publication of the Magnaporthe genome reveals this fungus to carry multiple cutinase genes. Why should a fungus reknown for its ability to push mechanically through the host cuticle carry so many such genes? Is there evidence for redundancy or do the cutinases play different roles in early adhesion, host recognition, adhesion of the appressorium, erosion of the plant surface to facilitate penetration or a combination of these factors? The project will address these points by classifying the cutinases, according to detailed transcript profiles, into early and late expressed genes. It will focus primarily on an early expressed cutinase, seeking its role in adhesion, perception of in triggering signal transduction via PKC and secondly on a late expressed cutinase, seeking its role in adhesion and /or penetration. The project seeks to link molecular biology with visual imagery in determining whether MAbBBG1 recognises Magnaporthe cutinase(s). Moreover, it seeks to exploit 3 closely related cutinases in the evaluation of a new vectorless gene silencing technique